Method of and apparatus for compressing and densifying a bowling pin impact zone



D. METHOD OF AND APEAR c. DOSKER 3,024,819

ATUS FOR COMPRESSING AND A BOWLING PIN IMPACT ZONE March 13, 1962DENSIFYING 5 Sheets-Sheet 1 Filed March 22, 1960 INYENTOR. coRNELu/s o.DOSKER ATTORNEY March 13, 1962 c. D. DOSKER 3,024,319

METHOD OF AND APPARATUS FOR COMPRESSING AND DENSIFYING A BOWLING PINIMPACT ZONE Filed March 22, 1960 5 Sheets-Sheet 2 FIG. ll

INVENTOR.

CORN ELIUS D. DOSKER ATTORNEY March 13, 1962 c. D. DOSKER 3,024,319

METHOD 0 ND APPARATUS FOR COMPRESSING AND ENSI NG A BOWLING PIN IMPACTZ0 D Filed March 22, 1960 Sheets-Sheet 3 INVENTOR. CORNELIUS D. DOSKEROMZMM ATTORNEY tuclry Filed Mar. 22, 1960, Ser. No. 18,217 12 Claims.(Cl. 144-320) This invention relates to methods for compressing anddensifying the ball-impact belly of a bowling pin. The impact zoneextends horizontally around and vertically across the belly of the pin.It may be viewed as being centered more or less on either or both thepins equator and its ball-line. The equator is a surface line whichencircles the pin in the horizontal plane of its maximum belly diameter.The ball-line is a surface line along which a bowling ball normallystrikes an upright pin and, it encircles the pin on a horizontal planelocated slightly below the equator. For the sake of clarity, we shallhereinafter view the impact zone as being centered on the equator. Thisapplication is a continuation-in-part of my copending US. application,Serial No. 733,862, filed May 8, 1958, and formally abandoned.

It is old to compress and density the impact zone of a bowling pin toimprove its wearing characteristics. The prior art does this by forcingan oversize pin axially through a heated and tapered sleeve as shown inthe U8. Patent, No. 2,652,081, to Curtis. This method compresses theequator of the pin, but does not compress it much above or below thisline. The compressed area of the pin is thus limited to a rather narrowband encircling the belly at its equator with definite boundary linesbetween the compressed and uncompressed areas of the pin. I have foundthat the wearing characteristics of the pin may be very substantiallyimproved by compressing it substantially above and below the equator aswell as along its equator, and that this can be accomplished withoutnecessarily creating any definite boundary lines between the compressedand uncompressed areas of the pin.

The principal object of this invention is to provide a method forcompressing the impact zone or belly of a bowling pin substantiallyabove and below its equator as well as along its ball-line.

Another object of this invention is to provide a method of compressingthe impact zone of a bowling pin without producing definite demarcationor boundary lines be. tween the compressed and uncompressed areas of thepin.

These objects are attained by positioning an oversized bowling pinbetween three circumferentially spaced concave rollers rotating on axesparallel to the longitudinal axis of the pin, the rollers having aconcave curvature of a slightly less degree than the longitudinal convexcurvature of the pin belly, moving the rollers together to compress thepin belly and simultaneously turning the pin between the rollers. Theserollers may be either heated or unheated, although preferably they areunheated. The rollers are forced together in a manner such; as toinstitute compression at and across said equator but only partiallyacross said impact zone and thereafter progressively increase the degreeof compression at said equatorup to a predetermined amount andcontemporaneously widen the band of compression across said zone in aprogressive manner proceeding in both directions vertically away fromsaid equator while maintaining a compressive pressure gradient whichalso progressively decreases in both directions proceeding verticallyaway from said equator. The compression operation is continued until theimpact zone or belly of the pin is compressed substantially to its finalsize along its equator. This operation etfectsa maximum degree ofcompression at said equator and a United States Patent progressivelydecreasing degree of compression proceeding in both vertical directionsaway from the equator to the upper and lower edges of the rollers wherethe compression is substantially zero. This provides a compressed impactzone which progressively blends in with the uncompressed areas of thepin, thus eliminating any definite demarcation lines between thecompressed and uncompressed areas of the pin and any abrupt changes ofthe degree or amount of compression or densification of the woodproceeding vertically across the impact zone. This elimination ofdefinite demarcation lines between the compressed and uncompressed areasof the pin progressively ioins or blends the high stressed areas in thepin around its ball-linc with the low stressed areas (the: uncompressedareas) of the pin, instead of joining them abruptly, and is one reasonwhy a bowling pin treated by my method possesses improved wearingcharacteristics as compared to those pins treated by the prior artmethods.

A bowling pin may be compressed without applying a suitable resin to thepin belly, or, preferably, the impact belly of the pin is coated with asuitable resin prior to its compression to set the wood fibers aftercompression. The use of a resin wets the wood fibers and reduces theirtendency to separate during compression, in addition to aiding inholding the fibers in their final compressed state.

After the bowling pins belly is compressed, the pin is turned to itsfinal size, where necessary, or it may be only sanded to smooth itssurface. During this step, little or no wood is removed-from the equatorof the pin belly as this was compressed to substantially final sizeduring the compression step.

The invention is illustrated in the accompanying drawings wherein:

FIG. '1 is an elevational view of an oversize bowling pin having itsfinal size or profile indicated in dotted lines;

FIG. 2 is an elevational view illustrating the oversize bowling pinhaving its lower surfaces sealed with wax;

FIG. 3 is an elevational view of the bowling pin of FIG. 2, having itsbelly surfaces coated with a suitable resin;

FIG. 4 is an elevational view of the bowling pin of FIG. 3 having itsbelly initially engaged with a compression roll;

FIG. 5 is an elevational view of the bowling pin of FIG. 4 in the finalstates of being compressed against a compression roll;

FIG; 6 is a perspective view illustrating the three circumferentiallyspaced compression rollers used to compress the bowling pin;

FIG. 7 is an elevational view of the compressed bowling pin being turnedto final size;

FIG. 8 is a side elevational view of a bowling pin compression machine;

FIG. 9 is a cut-away top plan view of the machine of FIG. 8;

FIG. 10 is a fragmentary bottom plan view of the left end of thecompression machine;

FIG. 11 is a fragmentary elevational view of the machine illustrating abowling pin positioned in the machine;

FIG. 12 is an elevational view of an oversize bowling pin used inamodified method and showing it before having its belly compressed;

FIG. 13 is an elevational view of the bowling pin of FIG. 12 having itsbelly compressed following the modified method;

FIG. 14 is an enlarged fragmentary vertical section 0 the belly of abowling pin, lying on its side, before compression by the modifiedmethod, With the dotted lines Patented Mar. 13, 1982 METHOD-FIGS. 17

The specific embodiment illustrated in FIGS. 1 to '7 of the novel methodof making a compressed belly bowling pin includes five steps. These are:forming an oversize bowling pin; sealing the lower surfaces of the pin;applying resin to the pin belly; compressing the pin belly betweenconcave rollers; and turning the compressed pin to final size.

Oversize Pin The oversize bowling pin 1 of FIG. 1 is similar toconventional bowling pine with the exception that it is about inchoversize, i.e. inch larger than the size desired in its final form. Thewood fibers in the pin 1 run vertically between the ends of the pin, thesame as in conventional pins. It is conventionally made by turning downa suitable block of maple :wood, which may be a single piece of wood,but preferably is a composite of several pieces bonded together.

The final size or profile of the pin is indicated in FIG. 1 by thedotted lines 2 running parallel to and spaced slightly inward from thesolid lines indicating the oversize pins sides. The pin 1 includes threemajor portions, a head 3, a belly or impact zone 4 and a base 5, thehead 3 being that portion located above the horizontal dotted line 6,the belly 4- being between the horizontal dotted lines 6 and 6' and thebase 5 being below the horizontal dotted line 6'.

Sealing Lower Surfaces The surfaces of the base 5, below the belly 4 ofthe oversize pin 1, are sealed with wax or other suitable substance byimmersing the base of the pin in a bath 8 of heated sealing wax up tothe horizontal dotted line 6, as shown in H6. 2. This treatment sealsthe wood pores of the base surfaces against the entry of resin duringthe following resin applying step. Thi is only one of the Ways that thelower surfaces of the pin may be sealed. This step may be omitted whenit is not desired to protect the lower surfaces of the pin from theresin during the resin applying step.

Applying Resin The belly 4 of the pin 1 is coated with a suitable resinby immersing the belly in a resin bath 9 to the horizontal dotted line6, as shown in FIG. 3. Only the belly surfaces contact and absorb theresin since the base surfaces are sealed with wax. This keeps the basesurfaces from absorbing resin and increasing the pins weightunnecessan'ly. The resin wets the wood fibers, for the followingcompression steps, and cures after the compression step to aid inholding or setting the fibers in their com-pressed state. As an exampleof a suitable resin, an epoxy resin may be used with a plasticizer addedto provide the resin with the proper amount of flexibility in its curedstate. A further example is a nylon resin dissolved in a volatilesolvent. It should be understood that immersion is only one way ofapplying the resin and that it might be applied in other ways, forexample, by spraying.

Compressing Pin Belly The belly 4 of the oversize pin 1 is compressed bysimultaneously squeezing and turning it between three or more concaverollers rotating on axes circumferentially spaced around the pin andextending parallel to the pins longitudinal axis. This. step isillustrated in FIGS. .4 to

4 6. FIG. 6 shows the three concave rollers 10, 11 and 12 positionedaround a pin.

Each of the rollers 10, 11 and 12 have identical concave curvatures.This concave curvature is slightly less (has a greater radius) than thevertical convex curvature of the oversize pin belly 4 so that therollers compress the pin belly equator a maximum amount and the rollerportions above and below the equator compress the pin bellyprogressively lesser amounts the farther they are spaced from theequator until reaching the end edges of the roller concavity wherelittle or no compression of the pin takes place. This makes it possibleto eliminate any definite demarcation lines between the compressed anduncompressed areas of the pin 1. This difference between the curvaturesof the pin belly and the roller is shown in FIG. 4, illustrating theinitial engagement of the pin belly 4 with the roller 12 as the rollers10, 11 and 12 are initially forced together on the pin. The concavecurvature of the roller 12 being less than the vertical curvature of thepin belly 4, the initial engagement between the roller and the pin bellyis limited to the pins equator. The rollers 10, 11 and 12 may be eitherheated or unheated, but preferably they are unheated.

At-least one and preferably two of the rollers 10, 11

and 12 are rotated about their vertical axes and their engagement withthe pin 1 turns and rotates it about its longitudinal axis between allthree rollers. As the force squeezing the rollers against the turningpin belly is slowly and progressively increased, the rollersprogressively rollcompress the pin belly surface with the maximum amountof compression taking place at the equator of the pin belly, due to thelesser degree of curvature of the rollers. The force squeezing therollers together on the pin is controlled to compress the oversize pinabout Ma inch at its equator, thus compressing the pins equator tosubstantially its final size, the pin being about A; inch oversize. Thisstage of the pin compression is seen in FIG. 5. Note that in FIG. 5, theupper and lower edges of the roller 12 are not pressed into the pin, butare aligned with the uncompressed surfaces of the pin. Actually, due tothe spring-back of the wood fibers after the release of the pin from therollers, the rollers may be controlled to compress the pin slightly morethan M; inch at its equator so that, after it is released and the woodfibers have sprung back, the pin remains compressed about A; inch at itsequator.

Turning to Final Size After releasing the compressed pin from itscompression rollers, itis placed in a lathe and turned to final size asshown schematically in FIG. 7. During this final turning, very little orno wood is removed from the equator of the pin belly as the pin wascompressed to final size at this point by the compression rollers. Thedotted lines 2- indicate thefinal profile of the pin after it has beenfinally turned.

COMPRESSION MACHINEFIGS. 8-11 The machine for roll-compressing a bowlingpin belly comprises a frame 19 including a lower plate 20, an upperplate 21 overlying and vertically spaced from the lower plate 20 and aplurality ofvertical posts 22, one at each pair of. vertically alignedcorners of the plates 20 and 21, rigidly interconnecting the platestogether.

The left end of the frame 19 carries a pair of transversely spacedconcave rollers 10 and 11 pivotally mounted on parallel-vertical axesbetween the lower and upper plates 20 and 21 with the ends of therollers journalled in suitable bearings fixed on the-respective lowerand upper plates. Each of the rollers 10 and 11 are equally spacedtransversely on the opposite sides of the longitud inal center line ofthe frame 19 with the spacing between the facing surfaces of the concaverollers being about 25% less'th'an the corresponding width of thebowling pin belly that is to be compressed by the rollers;

The third concave roller 12 is pivoted on a vertical axis extendingthrough the longitudinal center line of the frame 19 with its endsjournalled in bearings carried at the free ends of a sliding U-shapedcarriage 23 having upper and lower horizontal legs 24 joined by avertical bight 25. The U-shaped carriage 23 is dimensioned to slidesnugly between the lower and upper plates 20 and 21 along thelongitudinal center of the machine frame 19, and is guided during itstravel by guide bars 26 fixed respectively to the opposing faces of thelower and upper plates 20 and 21.

As previously explained, the rollers 10, 11 and 12 may be either heatedor unheated. No means is shown for heating the rollers, but this may bedone, for example, by electric heating coils embedded in the rollers.

The upper plate 21 has a pear-shaped hole 27 through which a bowling pinis inserted into and removed from the machine. To compress a pin belly,the pin is dropped base-down through the hole 27 and the roller 12 isforced against the pin, which in turn forces the pin against the otherrollers and 11, while the rollers 10 and 11 are slowly rotated inunison.

The mechanism for slowly rotating the rollers 10 and 11 is mounted atthe left end of the frame 19 and includes a motor 29 fixed on the upperplate 21 and having a pinion 30 keyed on its shaft. The pinion 30 drivesa larger gear 31 fixed at the upper end of a vertical shaft 32 that isjournalled in bearings fixed to the lower and upper plates and 21. Thelower end of the shaft 32 projects below the lower plate 20 and has agear 33 fixed thereto which is in simultaneous driving engagement withpinions 34 and 34' fixed to the respective lower ends of the rollers 10and 11. Hence, the motor 29 drives the rollers 10 and 11 through itspinion 39, gear 31, shaft 32, gear 33 and respective pinions 34 and 34'fixed to the rollers 10 and 11. In an example machine, I have selectedthe motor speed and gear ratios so that the bowling pin being compressedis rotated between the rollers 10, 11 and 12 at about 11 rpm.

The mechanism for forcing the traveling roller 12 toward the rollers 10and 11 includes a hydraulic jack 36 interposed between the rear of theU-shaped carriage bight and a vertical I-beam 37 fixed at the right endof the frame 19 between the lower and upper plates 20 and 21. Thehydraulic jack is operated from a suitable hydraulic pump 38,schematically illustrated in FIG. 8.

An adjustable stop means is provided for limiting the forward travel ofthe roller 12 toward the rollers 10 and 11 and includes a horizontalcross bar 39 mounted across the forward path of the U-shaped carriagebight 25. The cross bar 39 is attached at its opposite ends on verticalbraces 40 extending between the lower and upper plates 20 and 21 on theopposite sides of the U-shaped carriage path. A bolt 41, carrying a locknut, is threaded through the center of the cross bar 39 and can beadjusted to abut thebight 25 and stop the forward travel of the roller12 at a selected location.

MACHINE OPERATION Before operating the machine, it is assumed that thestop bolt 41 isproperly adjusted and locked in position to abut and stopthe carriage 23, carrying the roller 12, at the desired location whereina bowling pin is compressed the desired maximum amount. Also, thecarriage 23 is retracted for the machine to receive a bowling pin.

To operate the machine, the motor 29 is energized to drive the rollers10 and 11 at slow equal speeds, an oversized bowling pin 1 is dropped,base down, through the pear-shaped hole 27, and the pump 38 is actuatedto start moving the roller 12 toward the bowling pin. As soon as the pin1 is engaged between the three rollers 10, 11 and 12, it startsrotating, due to its being driven by the rollers 10 and 11. The roller12 also is driven about its axis by engagement with the rotating pin 1.

The hydraulic force of the hydraulic jack 36 pressing the roller 12against the pin 1 is slowly and progressively increased to apredetermined maximum value and the pin is slowly and progressivelycompressed until the carn'age 23 is stopped against the stop bolt 41which locks the roller 12 against further inward movement. In an examplemachine of mine, this predetermined value is 10,000 lbs. In this examplemachine, after the pin is in position between the rollers 10-12,hydraulic fluid pressure is admitted to the hydraulic jack 23 to movethe roller 12 inwardly until the pin is initially engaged by all threerollers -1012. The hydraulic pressure now is increased to institute thecompression of the wood. The pin usually rotates about six completerevolutions before the pressure in the jack 36 rises to thepredetermined maximum value and the carriage 23 is stopped against thestop bolt 41. Thereafter, the pressure is held at the predeterminedmaximum value while the pin rotates about three to five completerevolutions. Since this particular machine is designed to rotate the pinat about 11 r.p.m., the compression of the pin takes about one minute.

After the pin 1 is compressed sufiiciently, the hydraulic pressure inthe hydraulic jack 36 is released, the carriage 23 is retracted, and thepin I lifted upwardly through the pear-shaped hole 27, whereby themachine is ready to receive another oversize bowling pin.

MODIFIED METHODFIGS. 12-16 My modified method differs from that shown inFIGS. 1 to 7 by employing a starting bowling pin 45 having a slightlydifferent shape. Unlike the oversize bowling pin 1 in FIG. 1, which isoversize over substantially its entire surface, the starting pin 45,shown in FIG. 12, is of final or finished size substantially over itshead, neck and base portions 46-48 while its belly portion 49 isoversize. The extent to which the belly portion 49 is oversized, isindicated in FIGS. 14-15 by the crescent-shaped section 50 lying betweenouter line 51 representing the starting profile of the belly portion 49of the starting pin and inner line 52 representing the final or finishedcontour of the belly portion of the compressed pin; Within practicallimits, the radial and axial dimensions of section 50 may be varied inaccordance with the range of compression and densification desired. Ihave obtained good results with, and therefore prefer, a section 50having a radial dimension or thickness on the order of /a of an inchalong the ball line 53 and an axial dimension approximating 2% incheswith 1% inches on each side of the equator.

Prior to compression, the surface of the oversize belly portion 49 ofthe pin 45 is impregnated with or allowed to soak up some resinfollowing the same procedure as described in'connection'with the methodof FIGS. 1 to 7. Like the first method, this resin treatment ispreferably limited to the belly 49 in'order' to avoid increasing thepins weight unnecessarily and this may be done by covering the baseportion 48 of the pin with wax before dipping the pin in the resin, asshown in FIGS. 2 and 3.

After impregnation with resin, the oversize belly portion 49 of the pin45 is compressed by the machine shown in FIGS. 8 to 11 in substantiallythe same manner as that used in the FIGS. 1 to 7 method. The onlydifference is that the concave compression rollers have a slightlydifferent curvature. One of these rollers 54 is shown in FIGS. 12 and13. The concave curvatures of the peripheral surfaces of all rollers 54may be, and preferably are, the same. Such curvature, from one end ofeach roller to the other, may correspond precisely to the final verticalconvex curvature desired in the belly portion of the finished pin. Ifdesired, however, the periphery of the rollers 54 may be shaped so thattheir end portions remain out of contact with the pin as indicated at 55in FIG. 16. The final compressed pin 45 does not necessarily need to beturned on a lathe since it is compressed to final shape and size. It maybe lightly turned for smoothing purposes and then lightly sanded.Preferably it is lightly sanded only and this to the slight extentrequired to smooth its surface and prepareit for the application ofits'finish coatings.

The densification characteristics of the compressed bowling pin 45 areindicated in FIGS. 14 and 15, which respectively show the pins bellybefore and after compression. The dotted lines used in these figures areintended to illustrate density. Thus, in FIG. 14, the dotted lines areequally spaced to indicate that the wood is not compressed or densified.

In FIG. 15, the dotted lines are more closely spaced along the ball line53 of the pin than elsewhere. The spacing used in FIG. 15 is notintended to portray the changed density of the pin accurately but isintended generally to indicate that the densification of the wood is ata maximum along the circular equator 53 and that it progressivelydecreases not only radially in an inward direction from equator 53 butalso axially in opposite directions from equator 53. Accordingly, itwill be appreciated that, since the thickness of section 50 varied froma maximum at the equator 53 to zero at its upper and lower end edges,the increased density of the final pin changes progressively in a likemanner; hence, in proportion to th original thickness of section 50.

The actual ball-impact line or ball-line is located below the equator 53in order to impart a lift to the pin when it is hit by a ball. Withrepeated impacts, the conventional pin is compressed along the impactline. As a result, the lifting action of the impact is increased. Thisis objectionable. By precompressing this section, my invention tends toresist further compression by impact and correspondingly minimizes theincrease in lift which normally accompanies use.

Having described my invention, I claim:

1. A method of compressing and densifying the impact zone of a bowlingpin comprising: providing a bowling pin having an impact zone ofpredetermined convexity and equator diameter; placing said pin between aplurality of rotatable concave rollers providing a pin-receiving spaceof relatively less convexity than said predetermined convexity andhaving axes extending parallelto the longitudinalaxis of said pin in.said space; rotating at least one of said rollers; and progressivelyreducing the spacing between rollers so as to bring the equator of thepin into pin-rotating engagement with a corresponding portion of therollers and thereafter to compress the impact zone of the pin in aprogressive manner providing maximum compression along the equator ofthe pin and compression of progressively decreasing degree across theimpact zone in axial directions proceeding away from the equator. V

2. The method of claim 1 wherein: said rollers are heated.

3. The method of claim 1 including: before the compression step, thestep of coating the bowling pin with a suitable resin which wets thewood fibers to allow them to. be compressed more readily and which setsafter compression to lock the wood fibersin their compressed state.

4. The method ofclaim 1 including: compressing said pin to reduceitsequator diameter at least /s inch.

5. The methodof claim lwhereinz said compressing step is performed 'byatleast three concave rollers circumferentially' spaced around the:bowling pin.

' 6. The method .0f'.CiBiII1 5 wherein:. the spacing be- A 8tweentherollers is reducedby rnovingpne of-said rollers toward the otherrollers.-

7. The method of claim 1 including: compressingsaid pin to substantiallyits final equator diameter.

8. The method of claim 7 including; finishing the .compressed bowlingpin by cutting its surfaces to final size along those areas which arenot compressed in final size.

9. The method of claim 1 including: compressing the belly portion of thepin substantially to its final finished contour.

10. The method of claim 1 wherein: the providing step is performed byproviding a bowling pin having head, neck and base portionssubstantially of final finished size and an oversized belly portionwhich progressively decreases in oversize across the impact zone inaxial direc-' tions proceeding away from the equator; and therollerspacing reducing step is performed with rollers shaped to compressthe oversize belly portion substantially to final finished size.

11, A method of compressing and densifying a bowling pin having animpact zone extending horizontally around and vertically across thebelly of the pin and being more or less centered on an equator whichencircles the pin in the horizontal plane of its maximum belly diameter,com prising: providing a pin having a predetermined diameter at itsequator and a predetermined large convexity vertically across its impactzone; providing a plurality of concave compression members, each havinga concave cornpressing surface which is vertically dimensioned toembrace said impact zone and which is concavely curved to conform to apredetermined degree of vertical convexity smaller than said largeconvexity; and compressing the impact zone of said pin from said largeconvexity to ,a smaller convexity, said compression operation includingthe step of forcing said compression members compressively against theimpact zone of said pin in a manner such as to effect a maximum degreeof compression at said equator and a progressivelydecreasing degree ofcompression proceeding in both directionsvertically away from saidequator.

12. The method of claim 11 wherein said forcingstep is performed ina'manner such as to institute compression at and across said equator butonly partially across-said impact zone and thereafter progressivelyincrease the de gree of compression at saidequator' up to apredetermined amount and contemporaneously widen the bandof compressionacross" said zone in a progressive manner proceeding in both directionsvertically away from said equator while maintaining a compressivepressure gradient which also progressively decreases in both directionsproceeding vertically away from said equator.

References Cited in the file of this-patent UNITED STATES PATENTS 7

